Foraging ecology and parental behaviour in the common tern (Sterna hirundo)

One component of successful parenting is related to efficiency in foraging behaviour. The relationships among chick feeding, the size and type of food package, and length of parental foraging trips has not been well studied in seabirds. In addition, relatively few data have been collected on the activities of seabirds when foraging away from the nest site. The objectives of this study were: (1) to contrast productivity, feeding rate, and attendance patterns of individuals carrying a novel transmitter with a control group of birds; (2) to use radio-telemetry to assess the variability in foraging locations within and between individual male Common Terns; (3) to determine the seasonal variation in chick diet; (4) to determine for each transmittered bird, the relationships among the foraging patterns, parental behaviour, and seasonal reproductive success. The study took place over two years (1990-91) on a concrete breakwater 1 km offshore on Lake Erie near Port Colbome, Ontario. Ten pairs of terns in 1990 and 12 pairs in 1991 were radio-tracked by boat or car during the chick rearing stage. Concurrent behavioural observations documented the time each sex spent foraging or at the nest. The frequency and prey species composition of feeds to chicks were also recorded. The transmitters had negligible effects on the feeding frequency and brood attendance patterns of transmitter carrying birds. Peak nesting transmittered birds in 1990 and 1991 exhibited some inter-individual variability in foraging locations, however intraindividual variability was low. Birds foraged primarily to the west and northwest of the colony. Late nesters exhibited greater inter-individual variability, however intra-individual variability remained low for most birds. Neither group demonstrated sufficient variability to support the regular use of this colony as an "information centre". Individual transmittered birds had unique and predictable foraging patterns, and corresponding differences in feeding frequencies and brood attendance patterns, yet productivity was essentially equal between nests due to the impact and importance of stochastic events. Individuals that were recaptured in 1991 exhibited very similar foraging patterns to 1990, suggesting littie variability between years. Conservation of foraging patterns between years may have potential implications for mate choice decisions in future breeding seasons. Prey species delivered to chicks differed between morning and evening for peak and late nesters in 1990, but not 1991. Peak nesters in 1990 fed significantiy more Rainbow Smelt fOsmerus mordM) than Emerald Shiner (Notropis atherinoidesV this trend was reversed for late nesters who also fed large numbers of unidentified larval fish. No significant differences were found in 1991. Seasonal changes in prey species delivered to chicks is believed to be attributable to the temperature tolerances of the smelt and shiners, and the presence of large schools of larval fish during the late nesting season.

Habitat selection of three rodents in a frequently burned boreal environment : productivity and habitat diversity

How does fire affect the plant and animal community of the boreal forest? This study attempted to examine the changes in plant composition and productivity, and small mammal demography brought about by fire in the northern boreal environment at Chick Lake, N.W.T. (65053fN, 128°14,W). Two 5*6 ha plots measuring 375m x 150m were selected for study during the summers of 1973 and 197^. One had been unburned for 120 years, the other was part of a fire which burned in the spring of 1969. Grids of 15m x 15m were established in each plot and meter square quadrats taken at each of the 250 grid intersections in order to determine plant composition and density. Aerial primary production was assessed by clipping and drying 80 samples of terminal new production for each species under investigation. Small mammal populations were sampled by placing a Sherman live trap at each grid intersection for ten days in every month. The two plots were similar in plant species composition which suggested that most regrowth in the burned area was from rootstocks which survived the fire. The plant data were submitted to a cluster analysis that revealed nine separate species associations, six of which occured in the burned area and eight of which occured in the control. These were subsequently treated as habitats for purposes of comparison with small mammal distributions. The burned area showed a greater productivity in flowers and fruits although total productivity in the control area was higher due to a large contribution from the non-vascular component. Maximum aerial productivity as dry wieght was measured at 157.1 g/m and 207.8 g/m for the burn and control respectively. Microtus pennsylvanicus and Clethrionomys rutilus were the two most common small mammals encountered; Microtus xanthognathus, Synaptomys borealis, and Phenacomys intermedius also occured in the area. Populations of M. pennsylvanicus and C. rutilus were high during the summer of 1973; however, M. pennsylvanicus was rare on the control but abundant on the burn, while C. rutilus was rare on the burn but abundant in the control. During the summer of 197^ populations declined, with the result that few voles of any species were caught in the burn while equal numbers of the two species were caught in the control. During the summer of 1973 M. pennsylvanicus showed a positive association to the most productive habitat type in the burn which was avoided by C. rutilus. In the control £• rutilus showed a similar positive association to the most productive habitat type which was avoided by M. pennsylvanicus. In all cases for the high population year of 1973# the two species never overlapped in habitat preference. When populations declined in 197^f "both species showed a strong association for the most productive habitat in the control. This would suggest that during a high population year, an abundant species can exclude competitors from a chosen habitat, but that this dominance decreases as population levels decrease. It is possible that M. pennsylvanicus is a more efficient competitor in a recently burned environment, while C. rutilus assumes this role once non-vascular regrowth becomes extensive.

The utility of sedimentary diatoms as a measure of historical lake ph

As a result of increased acid precipitation, the pH of a large number of Canadian Shield lakes has been falling. Prior to this study there was no documentation available to explain the history of lake acidification for the Algoma area lakes. In order to obtain this information the diatom inferred pH technique was developed in this study. During two field seasons, July 1981 and July 1982, short sediment cores (circa 25-30 cm) were collected from 28 study lakes located north of Lake Superior, District Algoma, Ontario. The surface sediment diatoms (0-1 cm) from each of these lakes were carefully identified, enumerated, and classified in terms of their pH indicator status. The surface sediment diatom analysis indicated that lake pH is one of the most important factors affecting the species composition and relative abundance of diatom populations. Thus diatom assemblages can be sensitive indicators of lake acidification. When Nygaard's index alpha was plotted against observed lake pH, a statistically significant relationship resulted (r=-0.89; p=

Foraging ecology and parental care of common terns (Sterna hirundo) nesting in Windermere Basin, Lake Ontario

The relationships among chick feeding, size and type of prey item, and foraging time away from the brood have not been well studied in seabirds. This study investigated spatial and temporal patterns of foraging and chick-provisioning among 23 radio-tagged male common terns nesting at Hamilton Harbour, Lake Ontario during 1991 and 1992. Telemetry data were collected concurrently with behavioural observations from an elevated blind. Terns fitted with transmitters did not differ from controls with respect to either brood attendance, patterns of chick mortality, species and size distributions of prey delivered to offspring, or chick-provisioning rates. There was a clear separation of parental roles: males were primarily responsible for feeding chicks while females allocated more time to brood attendance. The prey species most commonly delivered to chicks by adults were rainbow smelt (Osmerus mordax) and alewife (A/osa pseudoharengus), followed in importance by larval fish, emerald shiner (Notropis antherinoides), salmonids, and fathead minnows (Pimepha/es prome/as). The relative proportions of various fish speCies delivered to chicks by males differed over the course of each breeding season, and there was also much variability in species composition of prey between years. Sizes of prey delivered to chicks also differed between sampling periods. The modal size of fish brought to chicks during Peak 1991 was 1.5 bill lengths, while the majority of prey in Late 1991 were small larval fish. The reverse trend occurred in 1992 when small fish were delivered to chicks predominantly during the Peak nesting period. During periods when predominantly small fish were delivered to chicks, the foraging activity of radio-tagged males was concentrated within a two kilometer radius of the colony. The observed variation in prey composition and foraging locations during the study likely reflects temporal variation in the availability of prey in the vicinity of the colony. Males delivered fish to chicks at a constant rate, while females 4 increased their feeding frequency over the first six to ten brood days. The mean length of fish delivered to chicks by adults increased significantly with increasing chick age. As a group, within each nesting period, transmittered males either foraged predominantly in the same directional bearing (north during Peak 1991, south during Late 1992), or concentrated foraging activity in the immediate vicinity of the colony (Late 1991, Peak 1992). However, individual radio-tagged males exhibited unique and predictable foraging patterns, often favouring specific locations within these areas and differing in their secondary foraging patterns. Overall, the Lake Ontario shoreline between NCB Bay" (3.5 km south of colony) and the lift bridge canal (4 km north of colony) was the foraging area used most frequently by radiotagged males during the chick-rearing period. Foraging patterns of transmittered males at Windermere Basin are similar to patterns of peak-nesting common terns, but differ from those of late-nesters, at a nearby colony (Port Colborne, Lake Erie). Differences between the foraging patterns of late-nesting terns at these colonies likely reflect differences in annual patterns of fish availability between the two locations. No relationship was found between foraging proficiency of adults and survival of offspring. Stochastic factors, such as predation by black-crowned nightherons (Nycticorax nycticorax) and adverse weather conditions during the early stages of chick rearing, may be more important determinants of common tern breeding success than parental quality or fish availability.

Characterizing the impact of multiple potential enemies (predators and parasites) on the behaviour of ranid tadpoles

In order to fully understand an organism's behaviours the interactions between multiple enemies or selective pressures need to be considered, as these interactions are usually far more complex than the simple addition of their effects in isolation. In this thesis, I consider the impact of multiple enemies (fish predators and parasites) on the behaviour of three larval anurans (Lithobates sylvaticus, L. clamitans and L. catesbeianus). I also determine whether species that differ in life-histories and habitat preferences possess different antipredator mechanisms and how this affects species responses to multiple enemies. I show that the three Ranid larvae respond differently to the trade-off imposed by the presence of both fish predators and trematode parasites within the environment. The two more permanent pond breeders (L. clamitans and L. catesbeianus) increased activity when in the combined presence of predators and parasites. In contrast, the temporary pond breeder (L. sylvaticus) decreased activity in the combined presence of predator and parasites, in the same manner as they responded to fish alone. Further, the presence of fish along with parasites increased the susceptibility of both L. sylvaticus and L. clamitans to trematode infection, whereas parasite infection in L. catesbeianus was unaffected by the presence of fish. A second experiment to assess palatability of the three anuran species to fish, revealed a range of palatabilities, with L. catesbeianus being least palatable, L. clamitans being somewhat unpalatable, and L. sylvaticus being highly palatable. This result helps to explain the species differences in tthe observed behaviour to the combined presence of fish and parasites. In conclusion, the results from this study highlight the importance of considering multiple selective pressures faced by organisms and how this shapes their behaviour.

Annual Variation in Bee Community Structure in the Context of Disturbance (Niagara Region, South-Western Ontario)

This study examined annual variation in phenology, abundance and diversity of a bee community during 2003, 2004, 2006, and 2008 in recovered landscapes at the southern end of St. Catharines, Ontario, Canada. Overall, 8139 individuals were collected from 26 genera and sub-genera and at least 57 species. These individuals belonged to the 5 families found in eastern North America (Andrenidae, Apidae, Colletidae, Halictidae and Megachilidae). The bee community was characterized by three distinct periods of flight activity over the four years studied (early spring, late spring/early summer, and late summer). The number of bees collected in spring was significantly higher than those collected in summer. In 2003 and 2006 abundance was higher, seasons started earlier and lasted longer than in 2004 and 2008, as a result of annual rainfall fluctuations. Differences in abundance for low and high disturbance sites decreased with years. Annual trends of generic richness resembled those detected for species. Likewise, similarity in genus and species composition decreased with time. Abundant and common taxa (13 genera and 18 species) were more persistent than rarer taxa being largely responsible for the annual fluctuations of the overall community. Numerous species were sporadic or newly introduced. The invasive species Anthidium oblongatum was first recorded in Niagara in 2006 and 2008. Previously detected seasonal variation patterns were confirmed. Furthermore, this study contributed to improve our knowledge of temporal dynamics of bee communities. Understanding temporal variation in bee communities is relevant to assessing impacts caused on their habitats by diverse disturbances.

Impact des perturbations anthropiques sur la végétation du complexe de milieux humides des Tourbières-de-Lanoraie

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal

Impact des coupes partielles sur l’activité de coléoptères phloeophages et xylophages en forêt boréale

Ce projet de recherche évalue la réponse à court terme de coléoptères phloeophages et xylophages (Cerambycidae et Scolytinae) à différentes intensités de coupes partielles (0, 25 et 40% de la surface terrière prélevée) afin de déterminer la viabilité de cette méthode sylvicole en forêt boréale. Disposant de 12 parcelles expérimentales (4 répétitions pour chaque intensité de coupe) dans une sapinière à bouleau blanc située au sud de la forêt boréale (Québec, Canada), nous avons évalué l’abondance, la diversité ainsi que l’établissement (taux d’attaque) de ces deux groupes d’insectes, et ce dès la première année suivant la coupe. L’échantillonnage a été réalisé à l’aide de pièges à interception multidirectionnelle et de l’écorçage de sections de 3 espèces d’arbres exposées dans l’ensemble des parcelles. Nos résultats montrent une plus grande activité/abondance des deux taxons (abondance 5 à 6 fois plus élevée) ainsi qu’une composition en espèces différente et plus diversifiée dans les peuplements partiellement coupés (25 et 40%). De plus, la présence et la distribution d’espèces colonisant habituellement des hôtes affaiblis (e.g., Trypodendron lineatum, Rhagium inquisitor) – et pouvant donc réduire la valeur économique d’arbres résiduels – a été recensée et semble être favorisée entres autres par l’ouverture de la canopée et des blessures physiques faites aux arbres pendant les opérations sylvicoles. Par ailleurs, l’approche combinant différentes techniques d’échantillonnage a permis une meilleure compréhension des mécanismes de localisation/sélection d’hôte (variant en fonction de l’espèce), un aspect important de la dynamique des insectes pour l’évaluation des risques suite aux coupes forestières. Sur la base de cette étude à court terme, il ne semblerait pas y avoir de différence significative sur les risques pour le milieu quant à l’augmentation d’activité des Cerambycidae et Scolytinae entre les deux traitements de coupe appliqués. Il reste cependant indispensable de vérifier la validité de ces résultats sur une plus longue période afin d’établir des plans d’aménagement forestier durables pour la forêt boréale.

Réponse de la communauté de mollusques aux perturbations physiques et chimiques dans un grand lac fluvial (Lac Saint-Pierre, Fleuve Saint-Laurent, QC)

Les mollusques sont des indicateurs de perturbations anthropiques et environnementales. Ce groupe de macroinvertébrés représente en outre une source importante de nourriture pour les poissons et les oiseaux aquatiques du littoral. Les hypothèses de cette étude sont que la communauté de mollusques est influencée indirectement par les tributaires agricoles et/ou par des variables environnementales (comme la dessiccation et l'exposition aux vagues) puisque ces perturbations sont susceptibles de modifier leurs sources alimentaires et leur habitat. Les indicateurs de la réponse des mollusques aux agents perturbateurs sont la composition, la diversité, la densité, ainsi que la biomasse des espèces. En septembre 2013, des mesures de paramètres physico-chimiques de l'eau ont été réalisées, et des échantillons de mollusques et de végétation aquatique ont été prélevés à 14 sites le long des rives du lac Saint-Pierre (Fleuve Saint-Laurent, Québec, Canada). Le long de la rive nord, les sites fortement exposés à l'action du vent, situés à de plus grandes élévations, affichaient une plus faible densité, biomasse et richesse spécifique de mollusques que les sites de la rive sud, en milieu plus abrité et profond. Les sites physiquement perturbés étaient caractérisés par de faibles biomasses en macrophytes submergés. Les sphaeriidae apparaissent comme des exceptions à ces patrons, montrant une abondance plus élevée aux sites presque dépourvus de macrophytes. Bien que les variables physiques et l'habitat exercent une influence déterminante sur les communautés de mollusques, les gastéropodes et les moules unionidés étaient également affectés par la dégradation de la qualité de l'eau dans le panache des tributaires agricoles. La richesse, la densité et la biomasse des gastéropodes étaient négativement influencées par des teneurs élevées de matières en suspension et de fer dissous. Les résultats de notre étude montrent que la communauté de mollusques du lac Saint-Pierre est directement affectée par l'émersion périodique, l'exposition au vent, et indirectement par l'effet de ces variables physiques sur les macrophytes qui constituent leur habitat.

Diversité et structure du zooplancton : importance pour la conservation de la biodiversité aquatique en zone urbaine

L'écologie urbaine est un nouveau champ de recherche qui cherche à comprendre les structures et les patrons des communautés et des écosystèmes situés dans des paysages urbains. Les petits plans d’eau sont connus comme des écosystèmes aquatiques qui peuvent contenir une biodiversité considérable pour plusieurs groupes taxonomiques (oiseaux, amphibiens, macroinvertébrés), ce qui en fait des écosystèmes intéressants pour les études de conservation. Cependant, la biodiversité du zooplancton, un élément central des réseaux trophiques aquatiques, n’est pas entièrement connue pour les plans d’eaux urbains et devrait être mieux décrite et comprise. Cette étude a évalué les patrons de biodiversité des communautés zooplanctoniques dans des plans d’eau urbains sur l’Ile de Montréal et leurs sources de variation. Des suggestions pour l’évaluation et la conservation de la biodiversité sont aussi discutées. La biodiversité zooplanctonique des plans d’eaux urbains s’est avérée être assez élevée, avec les cladocères et les rotifères montrant les contributions à la diversité gamma et bêta les plus élevées. Sur l’ensemble des plans d’eau, il y avait une corrélation négative entre les contributions à la bêta diversité des cladocères et des rotifères. Au niveau de chaque plan d'eau, la zone littorale colonisée par des macrophytes s'est avérée être un habitat important pour la biodiversité zooplactonique, contribuant considérablement à la richesse en taxons, souvent avec une différente composition en espèces. Les communautés zooplanctoniques répondaient aux facteurs ascendants et descendants, mais aussi aux pratiques d’entretien, car le fait de vider les plans d’eau en hiver affecte la composition des communautés zooplanctoniques. Les communautés de cladocères dans ces plans d’eau possédaient des quantités variables de diversité phylogénétique, ce qui permet de les classer afin de prioriser les sites à préserver par rapport à la diversité phylogénétique. Le choix des sites à préserver afin de maximiser la diversité phylogénétique devrait être correctement établi, afin d’eviter de faire des choix sous-optimaux. Cependant, pour des taxons tels que les cladocères, pour lesquels les relations phylogénétiques demeurent difficiles à établir, placer une confiance absolue dans un seul arbre est une procédure dangereuse. L’incorporation de l’incertitude phylogénétique a démontré que, lorsqu’elle est prise en compte, plusieurs différences potentielles entre la diversité phylogenétique ne sont plus supportées. Les patrons de composition des communautés différaient entre les plans d’eau, les mois et les zones d’échantillonnage. Etant donné les intéractions sont significatives entres ces facters; ceci indique que tous ces facteurs devraient êtres considérés. L’urbanisation ne semblait pas sélectionner pour un type unique de composition des groupes alimentaires, étant donné que les communautés pouvaient changer entres des assemblages de types alimentaires différents. Les variables environnementales, surtout la couverture du plan d’eau en macrophytes, étaient des facteurs importants pour la biodiversité zooplanctonique, affectant la richesse spécifique de divers groupes taxonomiques et alimentaires. Ces variables affectaient aussi la composition des communautés, mais dans une moindre mesure, étant des variables explicatives modestes, ce qui indiquerait le besoin de considérer d’autres processus.

Seasonal Studies on Primary Production and Associated Environmental Parameters in the Indian EEZ

The thesis describes the importance of Indian EEZ, definition and the various factors affecting primary production, general account of phytoplankton and its importance in marine ecosystem etc. In review of literature, general oceanography of Arabian Sea and Bay of Bengal and hydrography of eastern Arabian Sea and western Bay of Bengal. It deals with the distribution patterns of primary production, chlorophyll a, phytoplankton composition and particulate organic carbon in the eastern Arabian Sea and western Bay of Bengal during different seasons. Factors that affect primary productivity are irradiance, temperature, stability of the surface waters, nutrients and zooplankton grazing. The differential biological response of eastern Arabian Sea and western Bay of Bengal to monsoonal regimes. A precise estimation on the primary production of the entire EEZ of India on a regional basis and on a seasonal scale would be the only way to achieve any kind of predictive assessment on the fish stock and their sustainable yield. This study mainly envisages the qualitative and quantitative aspects on the magnitude of phytoplankton standing crop and production of organic carbon and their relationship to environmental characteristics during summer monsoon, Inter monsoon and winter monsoon periods in the east and west coasts of the Indian EEZ.This study revealed that the seasonality exerts a great impact on the biological production in the eastern Arabian Sea and western Bay of Bengal. High biological production may be the reason why most of the fish landings are Concentrated in the west coast of India than east coast. The present data on Phytoplankton production rate and the species composition will provide a meaningful ground for evaluations of exploitable renewable resources of the IndianEEZ

Studies on Some Aspects of Landings,Utilization and Export of Commercially Important Cephalopods

In the present study two aspects of cephalopod fishery such as (i) landings and (ii) utilization including export of cephalopods from Indian are dealt with. Under the topic landings, craft, both traditional and mechanized and fishing techniques employed for capturing cephalopods are discussed. General trend in cephalopod landing in India and particularly south west coast, species composition, description and geographic distribution of important species of cuttle fishes, squids and octopus and the distribution and abundance of cephalopods along the continental shelf of the south west coast are also discussed. Some biological aspects like population parameters, maturation and spawning, food and feeding of the two representive species of cuttle fishes and squid viz, Sepia pharaonis and Loligo duvauceli are studied.Under utilization, general handling and processing of various frozen cephalopods products for exports and commercial operation in a typical plant are studied. The export of cephalopod products since its commencement is studied in detail and market strategy for enhancing the export are suggested.

Studies on taxonomy and ecology of Mysidacea from the EEZ of India

Members of the order Mysidacea are important component in marine and estuarine plankton inhabiting all regions of the oceans. There are many brackish water species and few species occur in fresh water, some have become adapted to the specialized environments of caves and wells. They are omnivores, responsible for remineralisation of a substantial portion of the detritus in the water column. They form an important link in the food chain (between microbial producers and secondary consumers) and therefore play a major role in the cycling of energy within the aquatic ecosystem. In tropical and subtropical waters, swarms of mysids are exploited commercially and marketed as preserved cooked food. Mysids have been used in fish farming as live feed resource. They are also excellent experimental organism, extremely useful in the studies of potential impact of various pollutants in the aquatic environment. Mysids are also used in wood pulp effluent plants.Considering the significant role of mysids in the productivity of tropical and coastal ecosystems,the present study has been undertaken to extend our knowledge on the systematics, species composition, distribution,abundance and ecology of mysid fauna of the Indian EEZ and adjoining areas. The present study therefore will undoubtedly fumish valuable information on Mysidacea of the Indian waters.

Studies on some aspects of mangrove ecosystem in a tropical estuary"

The situation in the backwaters of Kerala, which reportedly had about 70,000 ha of mangroves, is unique in the sense that there has been a total conversion to other uses such as paddy cultivation, coconut plantation, aquaculture, harbour development and urban development In order to save and restore what is left over national and international organisations are mounting pressure on scientists and policy makers to work out ways and means conserving and managing the mangrove ecosystems. In this context, it has been observed in recent years that mangrove vegetation has remained intact in isolated pockets of undisturbed areas in the Cochin estuarine system and also that there is resurgence of mangroves in areas of accretion and silting. The candidate took up the present study with a view to make an inventory of the existing mangrove locations, the areas of resurgence, species composition, zonation and other ecological parameters to understand their dynamism and to suggest a mangement plan for this important coastal ecosystem

Ecology And Seasonal Variation Of Microalgal Community In An Oil Refinery Effluent Holding Pond: Monitoring And Assessment

The microalgal community as primary producers has to play a significant role in the biotic and abitoic interactions of any aquatic ecosystem. Whenever a community is exposed to a pollutant, responses can occur because individuals acclimate to pollutant caused changes and selection can occur favouring resistant genotypes within a population and selection among species can result in changes in community structure. The microalgal community of industrial effluent treatment systems are continuously exposed to pollutants and there is little data available on the structure and seasonal variation of microalgal community of industrial effluent holding ponds, especially of a complex effluent like that of refinery. The aim of the present study was to investigate the annual variation in the ecology, biomass, productivity and community structure of the algal community of a refinery effluent holding pond. The results of the study showed the pond to be a eutrophic system with a resistant microalgal community with distinct seasonal variation in species composition